The background of the Sino–British Joint Declaration was the pending expiration of the lease of the New Territories on 1 July 1997.
[4]The lease was negotiated between the UK and the
Guangxu Emperor of China, and was for a period of 99 years starting from 1 July 1898 under the
Second Convention of Peking. At the time of the lease signing, Hong Kong Island had already been ceded to the UK in perpetuity under the
Treaty of Nanjing in 1842 after the
First Opium War, and the southern part of the Kowloon Peninsula as well as the Stonecutters Island had also been ceded to the UK in perpetuity under the
Convention of Beijing in 1860 after the
Second Opium War.